-LRB- InStyle.com -RRB- -- The holiday season is also the engagement season !

A gorgeous cushion-cut stunner by Daniel K.

Yes , you read that right . It 's been said that nearly 40 percent of all marriage proposals occur between Thanksgiving and Valentine 's Day .

If you 're one of the lucky ladies hoping for a ring this season -LRB- or one of the nervous gentlemen contemplating popping the question -RRB- , use this guide to popular diamond shapes and cuts -- and the stars who sport them -- to get acquainted with the dazzling world of engagement rings .

Emerald

No shape more aptly fits the diamond nickname `` ice '' than the emerald , a rectangular cut with lean facets extending down the sides . This elegant art deco shape received its confusing name during the 1920s , when it was typically used for emeralds .

Characterized by a flat top and step-shaped side facets , an emerald cut cries out for a clean setting .

Star Power : Eva Longoria , Ellen Pompeo , Melania Knauss

Asscher

The Asschers of Amsterdam , gem cutters for the British royal family , designed this striking , dramatic shape in 1902 . A square with diagonally cropped corners and stepped sides , it features a high crown and sheds a gentle light .

Star Power : Tameka Foster , Ashlee Simpson , Christine Costner

Cushion

A square with curved sides and rounded corners , this stone shines softly instead of sparkling . Cushion-cut center stones surrounded by tiny diamonds are especially in vogue .

Star Power : Jeri Ryan , Courtney Ford , Guiliana DePandi

Princess

Think of this flirty , flashy option as the `` Yeah , baby ! '' stone , and not only because it was dreamt up in London during the swinging sixties . The arrangement of the gem 's many -LRB- 49 to 144 -RRB- facets produces a hall-of-mirrors effect .

Star Power : Stephanie March , Kara Janx , Sarah Michelle Gellar

Oval

Ovals have been enjoying a high profile since Tom Cruise placed a gorgeous one on Katie Holmes 's finger . The cool cousin of the round , the oval shares many of that stone 's features , with plenty of sparkle and versatility when it comes to settings . The long shape is especially flattering .

Star Power : Bridgette Wilson , Toni Braxton , Rebecca Romijn

Pear

Made to sit with the point facing up , this lusciously feminine -LRB- and unusual -RRB- cut frequently goes solo because few wedding bands fit easily beneath the large underside of this stone .

Star Power : Katherine Heigl , Lela Rochon , Tiffany Fallon

Marquise

The name for this cut comes from 18th-century Versailles , where courtiers wore ship-shaped rings as a sign of their rank . Today the marquise can be worn lengthwise or sailing sideways across the finger .

Star Power : Catherine Zeta Jones , Victoria Beckham , Portia de Rossi

Round

Created by Marcel Tolkowsky in 1919 , the round diamond is the most popular shape for engagement rings . It 's often called the round brilliant because it has triangular facets , arranged to direct light from the bottom of the stone up through the top for maximum sparkle .

Star Power : Katherine McPhee , Roselyn Sanchez , Mary J. Blige

Radiant

This rectangular stone , introduced in the seventies , lives up to its name : By combining long , lean , step-cut and triangular facets , it refracts lots of light . So if you decide on this shape , keep the setting simple .

Star Power : Heidi Klum , Leslie Grossman , Anna Chlumsky

Rose-Cut

Most diamonds have a flat top with facets on the edges and bottom , but a rose-cut diamond is domed and covered with facets . Carat for carat , rose-cut diamonds , which cast a mellow , soft light , are typically less expensive than other shapes .

Star Power : Melissa Akey

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Think of the flirty , flashy Princess cut as the `` Yeah , baby ! '' stone

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The name for the Marquise cut comes from 18th-century Versailles

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A rose-cut diamond is domed and covered with facets

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The round diamond is the most popular shape for engagement rings